I would be very careful when it comes to futures investing at the moment. The Bitcoin price just recently reached a new ATH and the volatility is quite high in the market. With a 3x leverage the risk of getting knocked out is quite, especially if your investment is only 100 USD. Do you have enough capital behind to cover losses and not be forced to liquidate? In case this is your only capital I would recommend you stick to the spot market. With a direct bitcoin investment you don't have to worry about get liquidated when prices are falling. You can just hold your coins long term and wait for prices to recover again. The only issue is that transaction cost are quite high at the moment, which makes small size trading not so profitable.